The Depuy ASR Artificial Hip Metal-on-Metal Design

In the previous post we looked at artificial hips and what should happen before a new medical device product like the Depuy ASR Hip gets to the marketplace. Now, let’s look a little deeper into the Depuy ASR hip system, its metal-on-metal cup and ball design, and how it failed:

What is “ASR” anyway?

“ASR” stands for “Articular Surface Replacement.” ASR is a surgical procedure that is an alternative to a total hip replacement procedure. In an ASR procedure, only the articular surface of the hip (the cup and the ball) is replaced. On the other hand, a total hip replacement includes not only the cup and the ball, but also a large piece of metal (known as a femoral stem) that is implanted deep into the patient’s femur and on which the ball is attached.

To market the Depuy ASR Hip for use in ASR surgery, the FDA would have required Depuy to undergo premarket approval, which would have required Depuy to conduct clinical trials, prove that the product is both safe and effective, and monitor the long-term safety and performance of the product once it was placed on the market. This could have saved much suffering.

However, Depuy apparently communicated to the FDA that the components of the Depuy ASR Hip would work for use in total hip replacement procedures and in some patients with conditions generally not conducive to the ASR surgery.

In essence, Depuy was able to put the Depuy ASR Hip on the market in the United States for use in a surgical procedure for which it was not designed: a total hip replacement. Despite being implanted in the bodies of thousands of individuals who believed the devices were or should have been safe, the Depuy ASR Hip has never been approved by the FDA as being safe or effective for ASR procedures, and the FDA never conducted a typical safety review of the Depuy ASR Hip.

The Depuy Hip used a metal-on-metal cup and ball design.

While most hip replacements use a cup made of plastics or other materials, Depuy’s ASR Hip uses a metal cup. By using a metal cup and a metal ball, the Depuy ASR Hip system forced metal to rub against metal with the full weight and pressure of the human body.

Because of the defective design of the Depuy ASR Hip, thousands of patients have been forced to undergo surgery to replace the failed implants. This is called a “revision surgery.”

Soon after Depuy launched the Depuy ASR Hip, failures were reported. Depuy would go on to receive thousands of similar complaints reporting that the Depuy ASR Hip had failed due to loosening of the cup and that the failure had forced patients to undergo painful revision surgeries to remove and replace the failed artificial hip. By the end of 2008, the number of premature failures had risen to more than three hundred (300) reports. These numbers have risen dramatically in the years since.

Depuy became aware that the Depuy ASR Hip was defective and that hundreds of patients already had been injured as a result of that defect. Experts have found that the data available to Depuy had shown for some time that the ASR has been failing early at a significantly higher rate than other medical devices.

In our next post, we will look at the terrible fallout from the high failure rates of the Depuy ASR Hip.